Vulcanization accelerator



United States Patent 2 VULCANTZATION ACCELERATOR Harald Bliimel, Otto Wiechulla, and Hermann Springmann, all of Marl, Germany, assignors to Chemische Werke Hills Aktiengesellschaft, Marl, Germany N0 Drawing. Filed Dec. 23, 1963, Ser. No. 332,834 Claims priority, application Germany, Jan. 25, 1963, C 28,993 16 Claims. (Cl. 260-795) This invention relates to'elastomer technology, particu substances, and also the corresponding compounds of selenium and tellurium. The function of these vulcaniza: tion accelerators depends on their ability to effect the cross linking of elastomers to produce technically useful vulcanizates within a reasonable time.

The principal object of this invention is to provide a new type of accelerator, particularly one that can be advantageously employed in unusually low concentrati-ons.

Other objects are to provide processes of vulcanization as well as vulcanizable and vulcanized compositions based on the new accelerators.

Upon further study of the specification and claims other objects and advantages of the present invention will 1 become apparent.

To attain the objects of this invention, it has been discovered that compounds of the formula wherein R is hydrogen or -a hydrocarbon radical of 1-10, preferably l-3 carbon atoms, and more preferably alkyl, can 'be used advantageously as vulcanization accelerators in vulcanizable rubber mixtures, particularly when such mixtures contain metal oxides.

The compounds can be produced by reaction of 1,2- epoxides with sulfur dioxide under pressure of about 20 to 70 atmospheres absolute and at elevated temperature of about 100 to 170 C., and if desired in the presence of a catalyst such as tetraethylene-ammoniumbromide, diethylene-aniline, pyridine.

The above substances are added in only relatively small amounts, ranging from 0.02 to 20%, and preferably from 0.1 to 5%, relative to the amount of elastomer.

Suitable vulcanizable elastomeric mixtures comprise, for example, rubber and equivalent synthetic rubber-like elastomers such as butadiene-styrene polymers, butadieneacrylonitrile copolymers, polychloroprene, polybutadiene, polyisoprene, butyl-rubber, ethylene-propylene copolymers in saturated or unsaturated condition, halogenated or halosulfonated polyethylenes; fillers such as activated or non-activated carbon black, activated or non-activated silicic acides, silicates, carbonates or sulfates; antioxidants,

"ice

antiozonants and the like; as well as waxes; fatty acids; plasticizing oils; coloring materials, etc.

The mixtures are produced with masticating mixes like those commonly used in the rubber industry, such as Banbury mixers and rubber mills. The basic mixtures without the vulcanizing ingredients are usually produced at elevated temperatures as well as the completed mixtures which consist of the basic mixtures with some cross-linking agents added therto to serve as vulcanizing agents. These elevated temperatures are in the range of 20 C. to 150 C.

As vulcanizing agents, those substances are included which alone or in admixture with other substances convert the elastomers, in admixture with other ingredients mentioned above, from the non-crosslinked into the crosslinked condition. For this purpose use is generally made of sulfur in its various forms, but also there can be employed selenium, tellurium, polysulfides and similar compounds of selenium and tellurium, polynitroso compounds, quinone derivatives, metal oxides or mixtures thereof such as zinc oxide, magnesium oxide, barium oxide, lead oxide, calcium oxide, etc.

The amount of vulcanizing agent is generally from about 0.1 to 10% by weight, based on the weight of the elastomer.

When sulfur is employed as the vulcanizing agent, it is also advantageous to employ a metal oxide, preferably zinc oxide in an amount equal to about 1 to 20% by weight of the elastomer.

Compared to prior art accelerators, the accelerators of this invention are advantageous with respect to the fact that they can be used in unusually low concentrations which is, of course, a major economic advantage.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specificembodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the specification and claims in any way whatsoever.

Example I The following mixture is formed in a masticating mixer of 2 liters net volume with the cooling water at 50 C.,

the mixer being operated at 40 r.p.m.:

TABLE 1 Parts Cold rubber, specifically a copolymer of about 23% by weight of styrene with about 77% by weight of butadiene prepared in an aqueous emulsion system at a temperature between 0 to 10 C., by using a free radical catalyst system Carbon black 47.5 Aromatic plasticizer oil, specifically one with an average molecular weight between 250 and 500, a viscosity-gravity-constant between 0.88 and 0.99 and a refractive index at 20 C. between 1.52 and 1.58 8 N-phenyl-N'-cyclohexyl-p-phenylene-diamine 1 Ozocerite 1 The mixing time is 10 minutes. The vulcanization materials noted in the following tables were added to the mixture in a laboratory rubber mill. This method'of producing the mixture, and the above basic composition, are also applicable to all of the subsequent examples.

The ring and plate formed samples which were obtained after vulcanization in a press at C. and subsequent stamping out were found to have the properties indicated in Table 2 when tested according to the German standardization instructions.

TABLE 2 Parts Vulcanl- Modulus, Per-man. Resist- Elasticity, per 100 Ingredients besides those zation Tensile ElongakgJcm. elongaance to Hardpercent Mixture parts of Table 1 time in strength, tion, tion, tearg ness,

N 0. rubber min. kgJcm. percent percent kgJcm. Shore 5 ZnO 15' A. 117 870 25 5e 51 16 5a 39 42 1 2 s a; as a e a a a a 5 Propylene glywl {120' D... 206 645 64 149 20 14. e 40 47 Example II 15 From this it will be seen that these compounds, in com- From this example, it will be seen that besides propylene glycol sulfite, homologous compounds are also effective in the same manner.

parison with the previously known vulcanization accelerators, can be used in unusually low concentrations.

Example IV 20 The complete eifectiveness of the vulcanization ac- TABLE 3 Parts Modulus, Perman. Resist- Elasticity, per 100 Ingredients besides those Heating Tensile Elongakg./em. elongaance to Hardpercent Mixture parts oi Table 1 time in strength, tion, tion, tearg., ness, No. rubber mm. kgJcm. percent percent kg.ab Shore Zn() 15A-- 127 795 33 72 41 19 54 38 41 1 i 2 a; as a a; a a a a a 8 4 5 l'z'bmylene glycfl sumte {120' D.-- 213 s45 67 153 23 59 as 45 5 ZnO .11.." 118 900 53 65 15 51 40 42 2 2 :2; a 88 a s 2 1: 7 111 5 3 5 Ethylene {120' D.-. 103 655 57 133 63 15 e0 39 46 The numerical values of the technical properties remain substantially constant within wide concentration Example III ranges, as Table 4 shows.

celerator requires the simultaneous presence of metal 5 of zinc oxide, other metallic oxides can be used.

oxides. Table 5 shows that an increased amount of zinc oxide produces improved vulcanization, and that instead TABLE 4 Modulus, Perman. Elas- Mixture Parts per Ingredients besides Heating Tensile Expans. kgJcm. expan- Resistance Hardticity,

N o. 100 parts those of Table 1 time in strength, percent sion, to tearg., ness, percent,

bb r mm kgJcm percent kg./cm. Shore 22 C.

5 Z o 153 835 38 85 35 18 55 39 1 2 s lf r 3 184 705 52 121 26 18 56 39 0. 1 Propylene glycol sulfite..- 213 655 68 153 24 16 58 39 226 600 81 177 20 15 59 39 5 ZnO 144 825 34 80 39 19 55 39 2 2 Sulfur 199 745 121 23 1s 5s 39 0.25 Propylene glycol sulfite... 206 635 68 150 23 16 58 39 220 609 82 176 19 15 59 39 5 135 850 33 75 42 19 39 3 2 180 775 46 107 35 19 56 4o 5 202 685 62 135 27 18 56 39 209 610 74 163 20 15 57 39 5 113 985 22 53 58 15 53 38 4 2 103 815 35 e9 41 17 55 as 1 202 715 50 122 30 16 57 38 229 630 69 161 20 14 39 5 99 855 25 53 56 15 52 39 5 2 162 835 38 88 41 16 55 38 2 193 720 52 118 27 16 57 39 193 609 152 20 15 60 40 5 124 905 29 61 51 15 53 38 6 z 825 39 94 33 17 55 as 4 705 54 124 25 16 56 39 189 585 67 153 19 13 59 39 5 106 990 26 55 56 15 51 38 7 2 160 820 39 87 34 16 55 38 6 194 750 51 119 31 16 56 39 120' D.-- 203 660 64 144 23 15 60 39 TABLE 5 Modulus, Perma- Reslst- Elasticity, llrllitxlture fozbrts per Ingredient bglsities those Electing glensitlfi E2pankg./cm. nent exance to Hardpercent 0. parts a e ime in s reng s on, pansion, teargo, ness,

rubber min. kg./cm. percent percent kgJcrn. Shore 2 Sulfur 15 A.-- 128 905 28 63 52 18 64 39 40 1 5 ZnO 30 177 815 39 92 36 20 55 40 43 5 Propylene glycol sulfite... 60 0.... 185 715 48 114 30 19 56 38 43 {120' D 209 695 57 132 25 17 59 38 45 ZnO A.... 153 870 34 77 45 18 55 38 41 2 2 Sulfur 30 13...- 201 770 50 117 36 19 57 38 43 5 as a is s a s :2 5 215 705 58 137 30 60 35 45 3. 2 226 545 54 201 15 15 61 43 53 5 214 480 107 11 13 60 44 53 200 475 95 11 13 60 44 48 5 BaO 15 A... 6 735 6 6 100 1 42 37 32 4 2 Sulfur 30' B.. 24 865 10 16 100 5 48 36 34 5 Propylene glycol sulfite. {60' 0...- 95 770 26 56 46 14 54 38 38 120 D 141 555 53 122 17 18 58 38 43 5 C210 15 A. 6 500 6 6 100 1 42 39 33 5- 2 Sulfur 30 B 6 760 6 6 100 2 45 39 33 5 Propylene glycol sulfit 60' 0...- 28 875 9 19 100 5 50 39 35 {120' D 95 715 29 61 45 14 55 40 38 Results similar to the preceding examples are obtained by replacing the cold rubber of Example 1 with natural rubber or any rubber-like vulcanizable elastomer such as those hereinbefore mentioned.

Similarly, higher homologues of the accelerators of this invention may be beneficially employed, such as 1,2 amylene, 1,2 hexylene, 1,2 heptalyne, 1,2 octylene, 1,2 nonylene, 1,2 decylene, 1,2 undecylene, and 1,2 dodecylene glycol sulfites.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Consequently, such changes and modifications are properly, equitably, and intended to be, within the full range of equivalence of the following claims.

What is claimed is:

1. In a process of vulcanizing a rubber with 0.ll0%by weight based on the weight of the rubber of a vulcanization agent, said rubber being selected from the group consisting of natural rubber and synthetic rubber-like vulcanizable elastomers, the improvement which comprises heating said rubber and vulcanization agent with a vulcanization accelerator of 0.02-20% by weight of the rubber, said accelerator being a compound of the formula:

wherein the accelerator is wherein the accelerator is 6. The process of claim 1, wherein the accelerator is employed in an amount of 0.1-5 based on the weight of the rubber.

7. A composition comprising a predominant amount of a rubber selected from the group consisting of natural rubber, and a synthetic, rubber-like, vulcanizable elastomer; 01-10% by weight based on the weight of the rubber of a vulcanizing agent; and 0.02-20% by weight based on the weight of the rubber, of a compound of the formula:

wherein R is selected from the group consisting of hydrogen and alkyl of l-lO carbon atoms.

8. The composition of claim 7, wherein the accelerator is ethylene glycol sulfite.

9. The composition of claim 7, wherein the accelerator is propylene glycol sulfite.

10. The composition of claim 7, wherein the accelerator is butylene glycol sulfite.

11. The composition of claim 7 wherein the vulcanizing agent is sulfur, and further comprising a metal oxide selected from the group zinc oxide, magnesium oxide, lead oxide, barium oxide and calcium oxide.

12. The composition of claim 7, wherein the accelerator is employed in an amount of 0.1-5 based on the weight of the rubber.

13. A composition as defined by claim 7 wherein the vulcanizing agent is selected from the group consisting of sulfur, selenium, tellurium, polysulfides, polynitroso compounds, quinone derivatives, and metal oxides.

14. A composition as defined by claim 8 wherein the vulcanizing agent is sulfur.

15. A composition as defined by claim 9 wherein the vulcanizing agent is sulfur.

16. A composition as defined by claim 10 wherein the vulcanizing agent is sulfur.

No references cited.

JOSEPH L. SCHOFER, Primary Examiner.

D. K. DENENBERG, Assistant Examiner. 

1. IN A PROCESS OF VULCANIZING A RUBBER WITH 0.1-10% BY WEIGHT BASED ON THE WEIGHT OF THE RUBBER OF A VULCANIZATION AGENT, SAID RUBBER BEING SELECTED FROM THE GROUP CONSISTING OF NATURAL RUBBER AND SYNTHETIC RUBBER-LIKE VULCANIZABLE ELASTOMERS, THE IMPROVEMENT WHICH COMPRISES HEATING SAID RUBBER AND VULCANIZATION AGENT WITH A VULCANIZATION ACCELERATOR OF 0.02-20% BY WEIGHT OF THE RUBBER, SAID ACCELERATOR BEING A COMPOUND OF THE FORMULA: 